LG 14z90 with Thunderbolt dock - Monitor does not wake from sleep-> resume

Discussion in 'LG' started by Superczar, Jul 18, 2021.

  1. Superczar

    Superczar Notebook Consultant

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    I have a HP G2 Thunderbolt dock connected to an external Monitor via display port (plus multiple peripherals)

    When docked to the LG 14Z90, everything works fine with no issues whatsoever.
    However, If I let the system go to sleep and resume afterwards, the external display does not wake up.

    In fact the external monitor comes back up (i.e. backlight comes on) but it does not seem to get a signal from the PC and goes to sleep after a few seconds.

    On the host PC itself, display settings show the second display (external monitor) as present but blanked out.
    The only way to fix it is to disconnect and reconnect the thunderbolt cable (or power cycle the dock, or hard power cycle the monitor)

    Everything works fine with all other systems (Macbook Air M1, Dell Latitude i7 7th gen with thunderbolt port, Lenovo L series i5 6th gen with USB C port- both have Intel graphics) - including charging, sleep/wake, 4K60 output as well as other USB peripherals. Sleep/ Wake work as expected

    I have tried most checks and fixes on the LG but sadly nothing seems to help - what would be the right way to perform a RCA on this?

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